Loop Flushing Valve Technical Information Manual...without a loop flushing valve, the addition of loop flushing improves fluid quality and generally extends transmission life. Consider

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Technical Information

Loop Flushing Valve

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Revision history Table of revisions

Date Changed Rev

Dec 2014 Danfoss Layout EA

Oct 2011 Backpage updated AB

Mar 2007 Update backpage AA

July 2003 First edition -

Technical Information Loop Flushing Valve

2 520L0641 • Rev EA • Dec 2014

General informationApplication..........................................................................................................................................................................................4Description..........................................................................................................................................................................................4Specifications.....................................................................................................................................................................................5Model code......................................................................................................................................................................................... 5Performance....................................................................................................................................................................................... 5Mounting.............................................................................................................................................................................................6

Service InformationAdjustment procedure................................................................................................................................................................... 8Service information..........................................................................................................................................................................8


Contents

520L0641 • Rev EA • Dec 2014 3

Application

The loop flushing valve, applied in a hydrostatic transmission circuit, maintains high quality of theworking fluid in the transmission power loop. While many transmissions can operate satisfactorilywithout a loop flushing valve, the addition of loop flushing improves fluid quality and generally extendstransmission life.

Consider the loop flushing valve when any of these exist:• Sustained operation at low pressure and high speed• Operation where continuous pressure exceeds 1000 hours per year• Cylinders in the hydrostatic circuit• Flow restricting valves in the power loop• Frequent operation of high pressure relief valves• Long power loop lines• Extraordinary life requirements

Danfoss recommends monitoring fluid quality under field operating conditions for extended periods oftime to determine loop flushing requirements. For a complete discussion of loop flushing and fluidquality, refer to Danfoss bulletins BLN-9886 Transmission Circuit Recommendations and 520L0463Hydraulic Fluids and Lubricants, Technical Information.

Description

The high pressure ports (1 and 2) of the valve are externally connected to the work or system auxiliaryports of the main hydrostatic transmission circuit. The valve drain port (4) must be externally connectedto the case drain return line of the transmission — preferably at the motor so that fluid flushes throughthe motor case and returns to the reservoir.

The shuttle valve exposes the low pressure side of the circuit to the charge relief valve. When properly set(see Adjustment procedure on page 8) the charge relief valve flushes a desired quantity of working fluidfrom the transmission power loop. The charge pump replaces this fluid.

You may specify a drain orifice to limit maximum flushing flow in circuits where the low side pressure ishigh or varies over a large range.

Schematic diagram

X

X

X

Orifice(optional)

Drain port 4

System press. gauge port 6

System port2

Charge press.

gauge port 3

System port1

System press. gauge port 5

P104 162E


General information

4 520L0641 • Rev EA • Dec 2014

Specifications

System pressure

Maximum high side 480 bar [6961 psi]

Maximum low side 70 bar [1015 psi]

Charge relief setting

Minimum 15 bar [218 psi]

Maximum 28 bar [406 psi]

Nominal charge relief settings are ±1.4 bar [±20 psi] and are set at a flow of 3.8 ±0.9 l/min [1 ±0.25 US gal/min] at 49º C [120º F]

Model code

8800485- -

Charge pressure 15 to 28 bar, 1 bar increments Example: 20 = 20 bar [290 psi]

Orif ce00 = None 09 = Ø 2.40 mm [0.0945 in.] 12 = Ø 3.19 mm [0.1255 in.]

i

Performance

Valve without orifice

0

100

200

300

400

500

600

6543210

FlowP104 185E

Maximum setting

Adjustment range

Minimum setting

Low

sys

tem

pre

ssu

re (a

bov

e d

rain

) (bar)(psi)

(US gal/min)

10

20

30

40

5

15

25

35

0 2 4 6 8 10 12 14 16 18 20 22(l/min)


General information

520L0641 • Rev EA • Dec 2014 5

Valve with 2.40 mm [0.0945 in.] orifice

0

1000

6543210

Flow

750

500

250

Maximum setting

Minimum setting

Adjustment range

Low

sys

tem

pre

ssu

re (a

bov

e d

rain

) (bar)(psi)

(US gal/min)

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16 18 20 22(l/min) P104 186E

Mounting

Installation drawing

Adjustable chargerelief valve1-1/16 in hex (locknut)1/2 in hex (adjustment)

9/16 in-18 SAE str. thd.O-ring boss system pressuregauge port 5

9/16 in-18 SAE str. thd.O-ring bossdrain port 4

9/16 in-18 SAE str. thd.O-ring bosssystem pressuregauge port 6

P104 163E

60.5[2.38]

95.0[3.74]

21.3[0.84]

14.0[0.55]

87.6[3.45]

78.2[3.08]

36.8[1.45]

36 max[1.417]

8.6[0.34]

15.9[0.625]

typical

80.8[3.18]

73.7[2.90]

15.2[0.60]

31.8[1.25]

Ø 10.7[0.42]

Mounting holes

60.7[2.39]

13.0[0.51]

9/16 in-18 SAE str. thd.O-ring bosscharge pressuregauge port 3

9/16 in-18 SAE str. thd.O-ring bosssystem port 1

9/16 in-18 SAE str. thd.O-ring bosssystem port 2

Third-angleprojectionmm [in]

Mount the loop flushing valve on any convenient flat surface that provides adequate support around thetwo mounting holes. Ensure the surfaces under the mounting bolts form a flat plane.

Failure to provide a flat mounting surface could create valve housing distortion when the mounting boltsare torqued. Housing distortion may bind internal components and reduce the drive and/or brakingcapacity of the system.


General information

6 520L0641 • Rev EA • Dec 2014

W WarningThe loss of hydrostatic drive line power in any mode of operation may cause a loss of hydrostatic brakingcapacity. A braking system, redundant to the hydrostatic transmission, must be provided which isadequate to stop and hold the system should such a condition develop.


General information

520L0641 • Rev EA • Dec 2014 7

Adjustment procedure

For initial setting of the valve package:

1. Plumb an in-line flow meter into the drain line.

If a flow meter is not available, use a clean container with a known volume and a stop watch tomeasure flow rate.

2. Set the brakes or otherwise restrict machine motion.3. Stroke the transmission pump to build at least 34 bar [500 psi] differential system pressure.4. Adjust the relief valve in the flushing valve package to obtain the desired drain flow. Typically 7.5 to

11.4 l/min [2 to 3 US gal/min] is sufficient. Rotating the adjusting screw counter-clockwise increasesflow and decreases the effective pressure setting by approximately 5 bar [73 psi] per turn.

5. Torque the locknut 42 to 55 N•m [31 to 41 lbf•ft].6. Verify that pump charge pressure is above recommended minimum.7. Remove the flow meter from the circuit.

Adjustment diagram

Relief valve adjustmenth1/2 in

Drain9/16 in - 18 str. thd.O-ring boss port

P104 165E

Locknuth1-1/16 int42 to 55 N•m [31 to 41 lbf•ft]

Service information

Component installation torque

Description Wrench size Torque

Gauge port plugs 9/16 in hex 27 to 47 N•m [20 to 35 lbf•ft]

Charge relief lock nut 1 1/16 in hex 42 to 55 N•m [31 to 41 lbf•ft]

Orifice plug 3/16 in internal hex 22 to 27 N•m [16 to 20 lbf•ft]

Shuttle spool plugs 11/16 in 36 to 44 N•m [27 to 33 lbf•ft]

Hose/tube fittings — 27 to 47 N•m [20 to 35 lbf•ft]


Service Information

8 520L0641 • Rev EA • Dec 2014

Exploded view

11

16

16A

13

16

16A

15

3

3

12

3A

3A

9

44A

2

2A

Enlarged bold type itemnumbers are recomended

parts to be stocked for servicing

2

2A

2

2A

15

1

t42 to 55 N•m [31 to 41 lbf•ft]h1-1/16 in

t27 to 47 N•m [20 to 35 lbf•ft] h 9/16 in

E101 098E

t 36 to 44 N•m [27 to 33 lbf•ft]h11/16 in

d

I 3/16 int 22 to 47 N•m [20 to 35 lbf•ft]

id

dd

d

d

dd

t27 to 47 N•m [20 to 35 lbf•ft]h 9/16 in




Service Information

520L0641 • Rev EA • Dec 2014 9

Replacement parts

Item Part Number Description Quantity

1 8800538 Housing assembly 1

2 9005100-5600 Plug 3

2A 9004201-3700 O-ring 3

3 9005100-5600 Plug 2

3A 9004201-3700 O-ring 2

4 9005100-5600 Plug 1

4A 9004201-3700 O-ring 1

9 8510012 Charge relief valve kit 1

11 9004201-6200 O-ring 1

12 8800242-0009 Orifice plug – Ø 2.40 mm [0.0945 in] 1 (opt.)

12 8800242-0011 Orifice plug – Ø 3.19 mm [0.1255 in] 1 (opt.)

13 8800550 Shuttle spool 1

15 513596 Spring guide assembly 2

16 518016 Special plug 2

16A 9004201-3700 O-ring 2


Service Information

10 520L0641 • Rev EA • Dec 2014


520L0641 • Rev EA • Dec 2014 11

Danfoss Power Solutions is a global manufacturer and supplier of high-quality hydraulic andelectronic components. We specialize in providing state-of-the-art technology and solutionsthat excel in the harsh operating conditions of the mobile off-highway market. Building onour extensive applications expertise, we work closely with our customers to ensureexceptional performance for a broad range of off-highway vehicles.

We help OEMs around the world speed up system development, reduce costs and bringvehicles to market faster.

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Go to www.powersolutions.danfoss.com for further product information.

Wherever off-highway vehicles are at work, so is Danfoss. We offer expert worldwide supportfor our customers, ensuring the best possible solutions for outstanding performance. Andwith an extensive network of Global Service Partners, we also provide comprehensive globalservice for all of our components.

Please contact the Danfoss Power Solution representative nearest you.

Local address:

Danfoss Power Solutions GmbH & Co. OHGKrokamp 35D-24539 Neumünster, GermanyPhone: +49 4321 871 0

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ContentsGeneral informationApplicationDescriptionSpecificationsModel codePerformanceMounting

Service InformationAdjustment procedureService information

Loop Flushing Valve Technical Information Manual...without a loop flushing valve, the addition of loop flushing improves fluid quality and generally extends transmission life. Consider

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